New MRI data discovers evidence of long-term brain damage in those infected with West Nile virus

A new study has discovered evidence of long-term brain damage in people infected with West Nile virus, regardless of whether they developed symptoms or not. Research presented at a meeting of the American Society of Tropical Medicine and Hygiene in November showed that many of those who presented with clinical disease continued to experience morbidity related to it up to eight years later.

About 4 in 5 people infected with West Nile virus do not have symptoms, and most others develop mild symptoms such as fever, fatigue, headache and body aches that eventually subside. However, neurologic and neurocognitive evaluations in 117 patients living in Houston, Texas, enrolled and tracked from 2002 to 2012 revealed that half suffered from abnormalities. Seven subjects had neurological abnormalities despite presenting with no symptoms of the virus at the time of initial infection, which was detected during a routine screening test for blood donors. Common problems included muscle weakness, abnormal reflexes, tremors, and signs of cognitive impairment.

The researchers also performed MRI scanning on 30 of the patients with neurological abnormality, who had significant cortical thinning compared to controls in both hemispheres. These subjects also had regional degeneration or atrophy in the cerebellum, brain stem, thalamus and other regions.

The results provide valuable information on the long-term consequences of infection with the virus, even in those who did not develop symptoms. The authors suggest that, following infection, patients should be regularly assessed for early signs of neurological deficits.